Patient-ventilator interaction: A general model for nonpassive mechanical ventilation

A general mathematical model for the dynamic behaviour of asingle-compartment respiratory system in response to an arbitraryapplied inspiratory airway pressure and arbitrary respiratorymuscle activity is investigated. The model is used to computeexplicit expressions for ventilation and pressure variablesof clinical interest for clinician-selected and impedance-determinedinputs. The outcome variables include tidal volume, end-expiratorypressure, minute ventilation, mean alveolar pressure, averagepleural pressure, as well as the work performed by the ventilatorand the respiratory muscles. It is also demonstrated that undersuitable conditions, there is a flow reversal that can occurduring inspiration.     

MANAGEMENT OF PATIENTS WITH HOMOCYSTINURIA REQUIRING SURGERY UNDER GENERAL ANAESTHESIA: A Case Report

An 8-year-old boy with homocystinuria required a prolonged dentaloperation under general anaesthesia. The successful management,without subsequent thromboembolism, is described. The patientshowed a partial response to treatment with pyridoxine overa two-year period. The response was marked by a reduction inthe plasma and urinary homocystine levels and by decreased plateletadhesiveness. It is suggested that a similar regime of pre-operativeand operative management should be considered in all affectedpatients undergoing surgery, since there was no increase inplatelet adhesiveness by the third postoperative day, as wouldnormally have occurred. ^*Present address: Department of Oral Surgery, St George's HospitalGroup, London.